Here are the factors for refinance:
LTV 85%: 0.48%
LTV 90%: 0.72%
LTV 95%: 1.04%.
For refinance: the above factor - 0.10%.
For example, if your loan amount is 270k, your value is 300k.
So LTV is 90%. Your mortgage insurance is:
270k * 0.72%/12= $162 per month.
Is it expensive? Yes, it is.
If the loan amount is: 285k, value 300k.
LTV will be 95%. Your mortgage insurance is:
285k*1.04/12=$247 per month.
So if your loan to value is over 80%, you need to compare the PMI and the rate with lender paid mortgage insurance. The difference for lender paid mortgage insurance is that the rate will be higher.
The above factors are from Radian. It will be different if the lender get the PMI from another company.